‘Is there anything sadder than a rusty, unused swing?’ mused reporter Anita Rani – settle down, she was in a school playground – near the beginning of the teasingly titled No Sex Please, We’re Japanese (BBC2).

Well, plenty, now you come to mention it. How about poverty, famine and global warming for starters?

Yes, I know that’s a bit high horse. But the missed opportunity in this look at the reasons behind Japan’s plummeting birth rate was enough to make the blood boil.

Coming at the subject from an entirely child-centric perspective, Rani bypassed any notion that the world simply can’t support an ever-increasing population and went straight for the nappy factor.

‘All the children have disappeared,’ she lamented, like a storyliner for The Returned, before taking herself off to a maternity ward, where she cooed: ‘Japanese babies are the cutest in the world!’ Holy hara-kiri, this was pretending to be a grown-up programme.

There was some interesting material. A too-short section featuring Japanese men, aged 38 and 39, who were obsessed with their virtual girlfriends, touched on the evolution of cyber-society.

But Rani soon dragged it back to Planet Nuclear Family. ‘What is going on with Japanese guys?’ she puzzled, asking one: ‘Don’t you want to get married?’

‘There are so many distractions,’ he replied. ‘Why would you want to get involved in something so messy?’ Fair point.

Turning her attention to Japan’s ageing population, Rani reckoned that Japan had ‘too few children, too many old people’.

For a moment I thought she was going to suggest a geriatric cull but she settled on immigration as the solution instead.

‘Everybody is Japanese here, so different to our multicultural society,’ she wittered through lenses so rose-tinted you could have scratched yourself on the thorns.

Not for one second did the thought occur that the trends happening in Japan might actually be a way of our overpopulated planet correcting itself.

Japan has led the world in many things – technology, raw fish, extreme flying – so here was a plausible portrait of the future world. But Rani only gave us the smaller picture.